Justification:
This species is listed as Endangered due to very small and restricted populations, where there are <250 wild born (non-reintroduced) mature individuals distributed among several reestablished populations. Of the 18 current sites where this species has been reintroduced, only three have viable populations. In 1987, this species was considered Extinct in the Wild, current populations have been the result of massive efforts to reintroduce captive animals back to the wild. Although formerly widespread in central North America, it currently exists only as reintroduced populations. The species declined throughout this century to near extinction by the late 1970's, primarily as a result of prairie dog control actions and sylvatic plague. However, after a captive breeding program, it was reintroduced by the United States Fish and Wildlife Service into eight western states and Mexico from 1991-2008. At present, it is considered self-sustaining at only three locations (two in South Dakota and one in Wyoming). Even with augmentation, wild ferret populations remain small, fragmented, and intensively managed.

Historically, black-footed ferrets were found throughout the Great Plains, mountain basins, and semiarid grasslands of west central North America - from southern Canada to northern Mexico wherever its prey, prairie dogs, were located (Hillman and Clark, 1980). The species was extirpated from most of its former range mainly as a result of prairie dog control programs and sylvatic plague - an exotic disease which was introduced to wild population. Today, they are known from 18 reintroduction efforts, only 3 of which are self sustaining. The three self-sustaining populations are in South Dakota and Wyoming; 4 populations of limited success in Arizona, Colorado, South Dakota, and Utah; 8 populations of recent initiation in Arizona, Kansas, Montana, New Mexico, South Dakota, and Mexico; and 3 declining or extirpated populations in Montana.

At present there are no known nonintroduced wild populations (Nowak, 2005), and only three of the populations contain mature individuals which were born in the wild. This species nearly went extinct in the late 1980s and existing populations are the success of massive efforts to reintroduce the species back to its native habitat. Captive breeding has been successful. Only several hundred individuals exist in captivity and in reintroduced populations in several US states and Mexico (Bard 2002).

Reintroduction began in 1991 with the release of a group of ferrets into the Shirley Basin of Wyoming. Since 1987, over 6,000 ferret kits have been produced through captive breeding and since 1991, over 2,000 ferrets have been released at 18 sites. All populations are sampled and counted two times a year as part of a management and recovery protocol. There are currently (spring count 2008) nearly 300 ferrets in captivity and approximately 500 breeding adults in the wild, less than 250 of which were actually born in the wild. These minimum population estimates occur in the spring. Maximum population estimates occur in the fall, include young of the year, and consist of an estimated 1,000 ferrets in the wild and 300 captive adults.

Black-footed ferrets are limited to open habitat, the same habitat used by prairie dogs: grasslands, steppe, and shrub steppe. It depends largely on prairie dogs: ferrets prey on prairie dogs and utilize their burrows for shelter and denning (Hillman and Clark, 1980). It has been estimated that about 40-60 hectares of prairie dog colony are needed to support one ferret. See Biggins et al. (in Oldemeyer et al. 1993) for information on evaluating areas as potential ferret habitat; factors include size of prairie dog complex, prairie dog population density, spatial arrangement of prairie dog colonies, potential for disease in prairie dogs and ferrets, potential for prairie dog expansion, abundance of predators, future resource conflicts and ownership stability, and public and landowner attitudes.

The extreme dependence of this mustelid on prairie dogs (Cynomys) made it especially vulnerable to extinction as its prey were persecuted as agricultural pests during most of the 20th century (Biggins and Godbey, 2003). Populations rapidly declined as a result of widespread extermination of prairie dogs and the spread of canine distemper and plague (Biggins and Godbey 1995, Biggins et al. 1998). Plague is an exotic disease that did not exist in North America prior to 1900. It can impact the ferret directly via infection and subsequent mortality, and indirectly through mortality to prairie dogs and resultant dramatic declines in the ferrets' prey base.

Populations of black-footed ferrets declined throughout this century to near extinction by the late 1970's (Biggins and Schroeder 1988). A small remnant population (around 100 animals or less; Schreiber et al. 1989) was discovered in 1981 near Meeteetse, in northwestern Wyoming, but that population was decimated by canine distemper and plague (Yersinia pestis) in 1985 (Forrest et al. 1988).

Another major threat for this mustelid is loss of habitat for conversion of grasslands to agricultural uses; the remaining habitat is now fragmented by great expanses of cropland and human development. In addition, the genetic diversity of the present introduced population is less than 90% of that present in the species prior to their decline in the wild. This decrease in genetic diversity has lead to increased inbreeding and may lead to decreased fitness due to inbreeding depression, including immune system dysfunction and reduced reproductive success (Bronson et al. 2007).

The black-footed ferret captive breeding program was initiated in October 1985 by the Wyoming Game and Fish Department in cooperation with the United States Fish and Wildlife Service. Eighteen black-footed ferrets were captured between 1985 and 1987 from the last-known population in Wyoming to start a captive breeding population (Miller et al., 1996), with the ultimate goal of reintroduction. Seven of those 18 individuals contributed unique genetic material for captive breeding and are considered founders. There are currently six institutions (one federal facility and five zoos) participating in the propagation program under the supervision of the United States Fish and Wildlife Service. Beginning in 1985, more than 6,000 black-footed ferrets have been born in captivity. Beginning in 1991, ferrets have been reintroduced at sites in eight Western U.S. states (Montana, South Dakota, Wyoming, Colorado, Utah, Arizona, Kansas, and New Mexico) and one site in Mexico (Bard, 2002; Bronson et al., 2007). The species is listed on CITES Appendix I and in listed in the U.S. Endangered Species Act.